Because I was at LeWeb in Paris for three days I missed the announcement, but Movable Type 5.2.2 is out (the first version using the new numbering scheme). The most important new features are the new 'Rainier' theme and an option to quickly add 'boilerplate text' to entries. The announcement & release notes are here.
I just gave the 'Rainier' theme its first whirl by building a quick blog here (it currently has some of my impressions from LeWeb in it). Try resizing your browser window (or view it on a phone/tablet) to see the design automatically resize things based on the available space, including the images. Nice!
Also, when a blog uses the 'Rainier' theme, the entry editor seems to automatically switch to a mode with the same column width, so you can actually see where line breaks etc. will happen.
As to the new 'boilerplate' feature, I haven't actually been able to find out how to use it. The manual says you can insert boilerplate texts in the edit entry screen once you have created one or more, but I can't seem to find a button for it right now.